1. Field of the Invention
The present invention relates to a method of forming a silicon carbide film on aluminum nitride, a film structure and a silicon carbide film.
2. Description of Related Art
A dense aluminum nitride has an excellent corrosion resistivity with respect to a halogen series corrosive gas. Moreover, the dense aluminum nitride is known as a high heat conductive material, and a volume resistivity thereof is larger than 108xcexa9xc2x7cm. In addition, the dense aluminum nitride has an excellent thermal shock resistivity. Therefore, it is assumed that a substrate for an electrostatic chuck and a heater used for a semiconductor manufacturing apparatus is preferably formed from aluminum nitride.
On the other hand, a method of forming a silicon carbide film on a surface of a substrate made of, for example, carbon by a chemical vapor deposition method is disclosed in Japanese Patent Publication Laid-Open publication No. 10-256108 (JP-A-10-256108). Such a silicon carbide film is dense and shows an excellent corrosion resistivity.
The inventors have investigated a silicon carbide film as a corrosion resistive member exposed to a corrosive gas in a semiconductor manufacturing apparatus in such a manner that the silicon carbide film was formed on a surface of the aluminum nitride substrate by the chemical vapor deposition method. Usually, the member used in the semiconductor manufacturing apparatus has a corner portion.
However, during this investigation the inventors found a phenomena such that the silicon carbide film peeled off at portions near the corner portion of the substrate. Such a silicon carbide film peeling off did not occur at a portion other than the corner portion, and the reason was not certainly understood. For example, as shown in FIG. 3, it is assumed that a silicon carbide film 4 is formed on a surface of a substrate 11. The substrate 11 comprises a first base plane 11a arranged upward, a second base plane 11c positioned downward to the first base plane 11a and a step plane 11b arranged perpendicularly between the first base plane 11b and the second base plane 11c. If the silicon carbide film 4 is formed on the substrate 11, the silicon carbide film 4 is not peeled off at near a corner portion 11d positioned downward, but the silicon carbide film 4 is sometimes peeled off at near a corner portion 11e positioned upward,
An object of the present invention is to provide a method of forming a silicon carbide film on a substrate made of aluminum nitride by a chemical vapor deposition method, which can prevent a silicon carbide film peel-off at near corner portions when the substrate has a step.
According to a first aspect of the invention, a method of forming a silicon carbide film on a substrate made of aluminum nitride by chemical vapor deposition includes a step of forming the silicon carbide film on the substrate made of aluminum nitride. The substrate includes a first base plane, a second base plane positioned downward with respect to the first base plane and a step plane arranged in an intersecting direction between the first base plane and the second base plane. One or more chamfered planes are arranged between the first base plane and the sup plane so as to form a plurality of corner portions each having an angle larger than 130xc2x0.
Moreover, according to a second aspect of the invention, a method of forming a silicon carbide film on a substrate made of aluminum nitride by chemical vapor deposition includes a step of forming the silicon carbide film on the substrate made of aluminum nitride. The substrate includes a first base plane, a second base plane positioned downward with respect to the first base plane and a step plane arranged in an intersecting direction between the first base plane and the second base plane. At least one round portion having a curvature radium of larger than 0.05 mm is arranged between the first base plane and the step plane.
Further, the other aspects of the invention relate to a film structure and a silicon carbide film, in which a silicon carbide film is formed on a substrate made of aluminum nitride in the manner mentioned above.